CK-12 Biology Workbook

About This Book

This workbook is published by CK-12 Foundation, a non-profit organization whose goal is to lower the cost of textbooks for students in kindergarten through 12th grade, both in the United States and around the world. CK-12 uses an "open-content" model — meaning teachers, experts, and other contributors work together online to build and improve free educational materials. This approach is called the FlexBook®, and it allows the Foundation to create high-quality textbooks that can also adjust to fit different students' needs.

The book is shared under a Creative Commons license (Attribution/Non-Commercial/Share Alike), which means people can copy, share, or adapt it for free, as long as they give credit to CK-12 and follow the license's rules. Anyone reproducing this book, in whole or in part, must include a link back to CK-12's website.

Authors: Margaret Lynch, Douglas Wilkin
Contributor: Doris Kraus
Editor: Douglas Wilkin

Table of Contents

This workbook covers a full year of high school biology, organized into 25 major units. Each unit contains several worksheet sections designed to reinforce key concepts.

Unit 1 – What is Biology? introduces science as a way of studying the natural world and defines biology as the study of life.

Unit 2 – The Chemistry of Life covers matter, organic compounds (molecules built around carbon, found in living things), chemical reactions inside organisms, and the special properties of water, acids, and bases.

Unit 3 – Cellular Structure and Function introduces cells, their internal structures, and how they transport materials while maintaining homeostasis (a stable internal environment).

Unit 4 – Photosynthesis and Cellular Respiration explains how living things capture and use energy, including how plants make sugar through photosynthesis, how cells generate usable energy through respiration, and how some organisms survive without oxygen (anaerobic respiration).

Unit 5 – The Cell Cycle, Mitosis, and Meiosis explores how cells divide, how chromosomes move during mitosis (division for growth and repair), and how meiosis produces reproductive cells.

Unit 6 – Gregor Mendel and Genetics covers Mendel's early experiments with pea plants and the basic rules of inheritance he discovered.

Unit 7 – Molecular Genetics: From DNA to Proteins explains the structure of DNA and RNA, how cells build proteins, how mutations (changes in genetic material) occur, and how genes are turned on or off.

Unit 8 – Human Genetics and Biotechnology looks at human chromosomes and genes, patterns of human inheritance, and modern biotechnology tools.

Unit 9 – Life: From the First Organism Onward traces Earth's formation and the origin of life, the rise of multicellular organisms, and how scientists classify living things.

Unit 10 – The Theory of Evolution presents Darwin's theory, the evidence supporting it, small-scale genetic changes in populations (microevolution), and larger-scale processes like the formation of new species (macroevolution).

Unit 11 – The Principles of Ecology introduces ecology as the study of how organisms interact with their environment, how matter cycles through ecosystems, and the world's major biomes (large regional ecosystems).

Unit 12 – Communities and Populations examines interactions within communities, features of populations, human population growth, the crisis of shrinking biodiversity, and natural resources and climate change.

Unit 13 – Microorganisms: Prokaryotes and Viruses covers prokaryotes (simple, single-celled organisms without a nucleus) and viruses.

Unit 14 – Eukaryotes: Protists and Fungi introduces protists and fungi, their roles in ecosystems, and their connections to human disease.

Unit 15 – Plant Evolution and Classification introduces the plant kingdom, the four major types of modern plants, and how plants evolved over time.

Unit 16 – Plant Biology explores plant tissues and growth, plant organs (roots, stems, and leaves), differences in plant life cycles, and how plants adapt and respond to their environment.

Unit 17 – Introduction to Animals gives an overview of animals in general and of invertebrates (animals without backbones) specifically.

Unit 18 – From Sponges to Invertebrate Chordates covers sponges, cnidarians (like jellyfish), flatworms, roundworms, mollusks, annelids (segmented worms), arthropods, insects, echinoderms (like sea stars), and invertebrate chordates.

Unit 19 – From Fish to Birds provides an overview of vertebrates (animals with backbones) and then examines fish, amphibians, reptiles, and birds individually.

Unit 20 – Mammals and Animal Behavior covers mammal traits, reproduction, evolution and classification, and general patterns of animal behavior.

Unit 21 – Introduction to the Human Body: Bones, Muscles, and Skin explains how the human body is organized and describes the skeletal, muscular, and integumentary (skin) systems.

Unit 22 – The Nervous and Endocrine Systems covers how the nervous system and hormone-producing endocrine system work.

Unit 23 – The Circulatory, Respiratory, Digestive, and Excretory Systems explains how the body moves blood, breathes, digests food, and removes waste.

Unit 24 – The Immune System and Disease covers the body's general defenses, its specific immune response, immune system diseases, and how environmental problems affect human health.

Unit 25 – Reproduction and Human Development begins with the male reproductive system...